Helical optical pulse stretcher

Abstract

A pulse stretcher includes a single pass pulse stretcher. An optical system is arranged around the single pass pulse stretcher. A beam enters the single pass stretcher and is reflected in a helical path using the optical system for multiple passes through the single pass pulse stretcher. The single pass pulse stretcher can include two 90° prisms, with a beam splitter located therebetween. The optical system can include first and second prisms. At least one of the first and second prisms can be a roof prism. The first and second prisms can have at least one surface oriented so as to direct the beam into the helical path. The optical system can have at least one mirror, or a plurality of mirrors.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to pulse stretchers, and more particularly, to helical pulse stretchers for use in lithography applications.[0003]2. Related Art[0004]Lithography is a process used to create features on the surface of substrates. Such substrates can include those used in the manufacture of flat panel displays (e.g., liquid crystal displays), circuit boards, various integrated circuits, and the like. A frequently used substrate for such applications is a semiconductor wafer or glass substrate.[0005]During lithography, a wafer, which is disposed on a wafer stage, is exposed to an image projected onto the surface of the wafer by exposure optics located within a lithography apparatus. While exposure optics are used in the case of photolithography, a different type of exposure apparatus can be used depending on the particular application. For example, x-ray, ion, electron, or photon lithography each can require ...

AI Technical Summary

Benefits of technology

The present invention is a helical optical pulse stretcher that solves problems in the related art. It includes a single pass pulse stretcher with a helical path and an optical system for multiple passes through the stretcher. The optical system includes prisms and mirrors. The technical effects of the invention include improved pulse stretching and reduced dispersion.

Problems solved by technology

A difficulty in designing optical components used in microlithography is caused by the high power density involved during exposure.

The high intensity pulses, over time, damage optical components, such as lenses used in the projection optics, requiring frequent replacement of these optical components.

However, the volume of space available for the projection optical system with the lithographic tool is limited.

Consequently, the volume of space available for the pulse stretcher is also limited, often precluding the use of a large number of cascaded pulse stretchers.

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